'vaguely-illustrated' originates from the combination of 'vaguely' and 'illustrated'. 'Vaguely' comes from the Latin word 'vagus', meaning 'wandering' or 'indeterminate', and 'illustrated' comes from the Latin 'illustratus', meaning 'enlightened' or 'made clear'.

'Vaguely' evolved from the Latin 'vagus' through Old French 'vague', and 'illustrated' evolved from Latin 'illustratus' through Middle English 'illustraten'.

Initially, 'vaguely' meant 'wandering' or 'indeterminate', and 'illustrated' meant 'enlightened'. Over time, 'vaguely-illustrated' came to mean 'not clearly depicted'.